Interdispersion, also referred to as interspersion, of armature windings is well known in the art. See, for example, MacDonald U.S. Pat. No. 4,492,890.
In an AC generator, an interdispersed armature winding reduces unwanted harmonic components in the output voltage and, therefore, provides a more sinusoidal output waveform. In an AC motor, an interdispersed armature winding reduces unwanted harmonic components in the rotating magnetic field and, therefore, reduces internal losses and provides a more uniform speed-torque curve.
Typically an AC machine has an armature comprising a slotted armature core wrapped by an even number plurality of winding groups. In a single phase AC machine, each winding group forms a magnetic pole. Thus a two pole single phase AC machine has two winding groups, a four pole single phase AC machine has four winding groups, and so forth. In a three phase AC machine, each of the phases has the same number of winding groups, the number being an even plurality and equal to the number of magnetic poles. Thus in a two pole, three phase AC machine, each phase has two winding groups for a total of six winding groups. Similarly in a four pole, three phase AC machine, each phase has four winding groups for a total of twelve winding groups.
In one type of AC machine, each winding group comprises a plurality of one-turn coil (or hairpin) joined in series. Each coil has two generally parallel side portions which are disposed in non-adjacent slots. The side portions are joined at one end by an endturn which extends axially outward from one end of the armature core. Other and the side portions also have an end connection extending a uniform distance axially outward from the other end of the armature core for series connecting to its electrically adjacent coil of its respective winding group.
Each coil spans a uniform number of slots. However, in the case of an interdispersed armature winding, coil of one winding group are disposed in certain slots located between two adjoining coil of another winding group. Thus when the end connections of separated coil of one winding group are connected (separated connections), the end connections must span a greater number of slots than when end connections of non-separated windings are connected (non-separated connections).
In view of the fact that the end connections are of a uniform length, in order to physically make these connections, the end connections for the separated connections must be pulled radially outward so as not to interfere with the non-separated connections. Because the end connections must be pulled radially outward, the diameter of the armature winding is increased.
In many generators, devices such as current transformers or other windings are positioned on the armature. For example, Lundell-Rice generators include both stationary armature windings and stationary field coils. An increased diameter armature winding can require the field coils to be positioned longitudinally away from the armature windings, increasing the overall length of the machine.
Additionally, automation of the brazing of the windings is difficult because the connections when pulled outwardly are in unknown locations.
The invention is provided to eliminate these and other problems.